Having been ask d for a Christmas present ideas list a riv nut kit sprung to mind rarely used but ideal for a present but help. I can’t tell if riv nuts can be used with a standard pop rivet gun or if I’d need a “kit”
You need a kit. Riv nuts are pulled up by threaded mandrels. One end screws into the nut the other end, almost invariably left hand threaded, screws into the gun. Not as useful as might be expected. With smaller threads its easy to pull too hard and snap the mandrel. With larger ones its almost impossible to squeeze hard enough to fully compress the collapsing part of the riv nut to get the specified grip on whatever its inserted into. Inadequately compressed riv nuts tend to spin when you try to undo the fastener. Which can be frustrating.
Most of the gun and nut kits on general sale are more suited to simple electronic chassis type frame construction with screwdriver tightened fasteners. Put a spanner on bolt heads and they may well spin. Theoretically a spanner tightened bolt will increase the compression on the collapsing part giving better grip. In practice the effect is somewhat variable.
There are also considerable issues with matching material thickness with rivet design. If you investigate the market for such fasteners there are lots of different types that do their specified jobs well when inserted by properly set up production machinery. It all gets much harder for ordinary guy in the garage doing odd jobs. Back in my employed days I spent far too much time unwinding disasters caused by unreasonably optimistic scientists and lab rats trying to use those things. Properly specified and on appropriate jobs they work well but sorting the "proper" side of things can be a world of grief.
Lazy tongs type inserters are better as much more force can be applied so inherently stronger riv nuts can be used. Pneumatic types are probably best but they do need correct adjustment and are rather expensive. I have a standard "pop rivet gun" kit which does get some use but not on car jobs. Someday I shall insert 8 mm ones in the P38 chassis to fit my side steps. I shall make a screw jack lever tool specifically for the job. Need to track down the proper insertion force first. Too much force being almost as bad as too little
Thats a very good price for that style of riv-nut tool. In the UK mostly professional grade on offer with corresponding prices. Big beast tho'. Over a foot long but well up to inserting the heavier duty ones you need for car work. Need to be careful with the smaller sizes. Will snap an M3 mandrel almost without noticing! Especially if you get a bit out of line and don't pull up square. Easily done (how do I know!).
Where you intend to insert the riv nut matters. If there is no hole, you'll have to drill one. In the case of running boards, I was not able to drill holes in the frame in all the places they need to be due to a lack of space. I ended up having the running boards (side steps?) welded on.
these tools are good when fabricating things on the bench but when it comes to doing it in the car its space that is your enemy . also if its not done properly removal can be a problem, so it depends on weather it suits your application. expensive if for a one off use.
I’ve used Rivnuts extensively on many cars (and we use them by the thousand at work) and they can be successful – the biggest problem with a rivnut is they cannot handle excessive torque, especially when the fastener is being undone in the future – the rivnut spins out, and then you have a challenge of trying to remove it - here’s a few pointers (some of which have been mentioned already) that might help…
Hole diameter accuracy is crucial – if anything, er on the tight side – loose oversize holes are bad news - refer to the manufacturers data sheet or use a good vernier to measure the body of the rivnut - decimal points matter - a 9.2mm hole is a 9.2mm hole, not a 9.5mm hole!
By a quality tool from a reputable manufacturer – you will wear (or break) the mandrel, so you need to be sure replacements are easy to source.
For smaller threads (M4, M5 and M6) use a single handed grip tool, for larger sizes, go with a two handed scissor type puller – you’ll get better control over the pulling action - I'd personally avoid threads smaller than M4 as the mandrel is very weak once it gets this small.
As already mentioned, it can be real easy to pull the thread clean out of the rivnut if you over pull it, however if you buy a quality tool, you should be able to set it so you cannot over pull the rivnut – if in doubt, test 1[SUP]st[/SUP] in scrap of the same section.
Pulling the rivnut square is critical – breaking a mandrel in the rivnut does not add to the entertainment of the experience - before you start drilling, be sure you've got the room to use the tool (square to the face of the hole where the rivnut is to be applied) - you cannot have the tool at an angle whilst pulling, it must be perpendicular to the section.
Holes need to be round (I know, sounds daft, but cheap drills in thin metal often make holes that are not a good shape) – drill the hole undersize and ream it if necessary.
The positions of the drilled holes must be accurate – because of their low torque nature, a rivnut will not withstand a bolt being applied at an angle – your rivnut must be in direct alignment with the hole of whatever it is you’re bolting on.
Where you can, use splined rivnuts – these tend to grip the hole better and are less likely to spin out.
Source quality rivnuts suited to the gauge you’re applying them into – if you don’t, the grip will be poor, and they spin out – remember an “expensive” rivnut is only pennies more than a cheap one – buy on a quality, not cost basis.
Avoid the possibility of thread galling problems – either use zinc plated rivnuts with stainless bolts, or vice versa – if you use stainless in stainless and the thread binds up, it’s a messy job trying to get everything apart.
Closed end rivnuts are great where the end is exposed (into unseen damp cavities or through from inside the car to outside) – you’ll get less corrosion issues and are more likely to be able to release the fastener in the future.
Copper grease on threads in all situations is vital, however before applying the rivnut, ensure the area surrounding the hole is clean, dry and free from grease or oils (to ensure the grip is at its best)
My ’38 probably has over 100 rivnuts in it, all of which work fine – you just need decent tooling, decent fasteners and careful application.
I second all of the above. I didn’t buy a tool when I installed my rivnuts when installing the rear lamp guards and my rear ladder. Not the best results. Had to file the hole round and slightly bigger
puttingvthe bolts in didn’t line up and I had to add a normal lock but behind the ladder inside the rear hatch which was a huge PITA. Spend the money take your time and do it correctly.